From patchwork Fri Sep 7 16:50:57 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dominique Martinet X-Patchwork-Id: 10592373 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id ED367112B for ; Fri, 7 Sep 2018 16:51:25 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D7A052B90B for ; Fri, 7 Sep 2018 16:51:25 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id CBE092B90F; Fri, 7 Sep 2018 16:51:25 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 71C852B90B for ; Fri, 7 Sep 2018 16:51:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726394AbeIGVdE (ORCPT ); Fri, 7 Sep 2018 17:33:04 -0400 Received: from nautica.notk.org ([91.121.71.147]:38100 "EHLO nautica.notk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726738AbeIGVdD (ORCPT ); Fri, 7 Sep 2018 17:33:03 -0400 Received: by nautica.notk.org (Postfix, from userid 1001) id 49F5CC01D; Fri, 7 Sep 2018 18:51:15 +0200 (CEST) From: Dominique Martinet To: v9fs-developer@lists.sourceforge.net, Eric Van Hensbergen , Latchesar Ionkov Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Dominique Martinet Subject: [PATCH 4/4] 9p locks: fix glock.client_id leak in do_lock Date: Fri, 7 Sep 2018 18:50:57 +0200 Message-Id: <1536339057-21974-5-git-send-email-asmadeus@codewreck.org> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1536339057-21974-1-git-send-email-asmadeus@codewreck.org> References: <1536339057-21974-1-git-send-email-asmadeus@codewreck.org> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Dominique Martinet the 9p client code overwrites our glock.client_id pointing to a static buffer by an allocated string holding the network provided value which we do not care about; free and reset the value as appropriate. This is almost identical to the leak in v9fs_file_getlock() fixed by Al Viro in commit ce85dd58ad5a6 ("9p: we are leaking glock.client_id in v9fs_file_getlock()"), which was returned as an error by a coverity false positive -- while we are here attempt to make the code slightly more robust to future change of the net/9p/client code and hopefully more clear to coverity that there is no problem. Signed-off-by: Dominique Martinet --- fs/9p/vfs_file.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c index 73857ebaedfb..a25efa782fcc 100644 --- a/fs/9p/vfs_file.c +++ b/fs/9p/vfs_file.c @@ -208,6 +208,14 @@ static int v9fs_file_do_lock(struct file *filp, int cmd, struct file_lock *fl) if (schedule_timeout_interruptible(v9ses->session_lock_timeout) != 0) break; + /* + * p9_client_lock_dotl overwrites flock.client_id with the + * server message, free and reuse the client name + */ + if (flock.client_id != fid->clnt->name) { + kfree(flock.client_id); + flock.client_id = fid->clnt->name; + } } /* map 9p status to VFS status */ @@ -239,6 +247,8 @@ static int v9fs_file_do_lock(struct file *filp, int cmd, struct file_lock *fl) locks_lock_file_wait(filp, fl); fl->fl_type = fl_type; } + if (flock.client_id != fid->clnt->name) + kfree(flock.client_id); out: return res; } @@ -273,7 +283,7 @@ static int v9fs_file_getlock(struct file *filp, struct file_lock *fl) res = p9_client_getlock_dotl(fid, &glock); if (res < 0) - return res; + goto out; /* map 9p lock type to os lock type */ switch (glock.type) { case P9_LOCK_TYPE_RDLCK: @@ -294,7 +304,9 @@ static int v9fs_file_getlock(struct file *filp, struct file_lock *fl) fl->fl_end = glock.start + glock.length - 1; fl->fl_pid = -glock.proc_id; } - kfree(glock.client_id); +out: + if (glock.client_id != fid->clnt->name) + kfree(glock.client_id); return res; }